68513281 has 4 divisors (see below), whose sum is σ = 72543492. Its totient is φ = 64483072.

The previous prime is 68513257. The next prime is 68513287. The reversal of 68513281 is 18231586.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 26471025 + 42042256 = 5145^2 + 6484^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-68513281 is a prime.

It is a super-2 number, since 2×68513281² = 9388139346769922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (68513287) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2015080 + ... + 2015113.

It is an arithmetic number, because the mean of its divisors is an integer number (18135873).

Almost surely, 2^68513281 is an apocalyptic number.

It is an amenable number.

68513281 is a deficient number, since it is larger than the sum of its proper divisors (4030211).

68513281 is a wasteful number, since it uses less digits than its factorization.

68513281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4030210.

The product of its digits is 11520, while the sum is 34.

The square root of 68513281 is about 8277.2749742895. The cubic root of 68513281 is about 409.1899154474.

The spelling of 68513281 in words is "sixty-eight million, five hundred thirteen thousand, two hundred eighty-one".